Hello,
Well I can say that I first used RUI near when i first joined here (see join date) and it has been years and many orders with out issue (other then one time they send it back due to a mess up on the postal's end, some how they said address was not right and must have sent it back, but it was right, could have been a sorter who knows. but i got order regardless so w/e not rui's fault)
I have ordered the clen and most of the products. I don't see it being an issue.
I mean these are for research use only, so they have no reason to stop it other then inspect and then let it go through. (rarely do they even inspect it, it seems random actually)
You should be fine, there are a few Canadians here and I don't think they have had any issues either.
The only issue I ever heard of regarding Clen and customs was to aussie, because they are hard on that compound, but the rest seems fine.
For Canada you should not have any issues.
Hope that helps.